Movable lens mechanism

RELATED APPLICATIONS

0001This application claims the benefit of U.S. Provisional Application No. 60/610,439, entitled “Movable Lens Mechanism”, filed Sep. 16, 2004, which is incorporated herein by reference in its entirety.

BACKGROUND

0002This invention is related in general to microelectronic devices and more specifically to a microelectromechanical system (MEMS) zoom lens.

0003MEMS devices are desirable because of their small size, potential lower cost, and higher performance. Some types of devices that have been built using MEMS techniques include accelerometers, gyroscopes, temperature sensors, chemical sensors, atomic force microscope (AFM) probes, micro-lenses, combdrive actuators, piezoelectric actuators. As imaging devices become increasingly smaller, it is desirable to have a small, movable lens mechanism that can be integrated into a miniature imaging system. Such a lens would provide, for example, image zoom and focus capabilities.

SUMMARY

0004In one embodiment, a lens mechanism is made of a flexible support with a lens positioned on the support. A sensor is positioned below the lens so that it senses photons passing through the lens. At least one actuator is positioned around the lens such that a change in an electric charge on the actuator causes the lens to move. In one embodiment, the lens moves along its optical axis. In another embodiment, the lens moves so that its optical axis tips from the original orientation. In yet another embodiment, the lens moves due to a change in electric charge on an electrostatic charge layer that is coupled to the lens

0005One embodiment provides an apparatus comprising: a flexible support; a lens supported by the flexible support, the lens being aligned with a first plane; a sensor positioned to receive photons passing through the lens; and an actuator positioned such that a change in an electric charge on at least a portion of the actuator causes the lens to move to be aligned with a second plane, the second plane being substantially parallel to the first plane.

0006Another embodiment provides an apparatus comprising: a flexible support; a lens supported by the flexible support, the lens being aligned with a first plane; a sensor positioned to receive photons passing through the lens; and an actuator positioned such that a change in an electric charge on at least a portion of the actuator causes the lens to move to be aligned with a second plane, the second plane intersecting the first plane.

0007Another embodiment provides an apparatus comprising: a flexible support; a lens supported by the flexible support, the lens being aligned with a first plane; a sensor positioned to receive photons passing through the lens; and an electrostatic layer positioned adjacent the lens such that a change in an electric charge on at least a portion of the electrostatic layer causes the lens to move to be aligned with a second plane, the second plane being substantially parallel to the first plane.

0008Another embodiment provides an apparatus comprising: a flexible support; a lens supported by the flexible support, the lens being aligned with a first plane; a sensor positioned to receive photons passing through the lens; and an electrostatic layer positioned adjacent the lens such that a change in an electric charge on at least a portion of the electrostatic layer causes the lens to move to be aligned with a second plane, the second plane intersecting the first plane.

0009Embodiments of the invention can provide a dynamic actuator mechanism for positioning a small lens.

BRIEF DESCRIPTION OF THE DRAWINGS

0010<figref idref="DRAWINGS">FIG. 1</figref> is a schematic cross-sectional view that illustrates a lens mechanism in accordance with an embodiment of the present invention;

0011<figref idref="DRAWINGS">FIG. 2</figref> is a schematic cross-sectional view that illustrates a lens mechanism in accordance with another embodiment of the present invention;

0012<figref idref="DRAWINGS">FIG. 3</figref> is a schematic top plan view of a lens mechanism in accordance with embodiments of the present invention;

0013<figref idref="DRAWINGS">FIG. 4</figref> is a schematic perspective cutaway view of a lens mechanism in accordance with embodiments of the present invention;

0014<figref idref="DRAWINGS">FIG. 5</figref> is a schematic cross-sectional view that illustrates lens movement on a flexible support in accordance with embodiments of the present invention;

0015<figref idref="DRAWINGS">FIG. 6</figref> is a diagram of a cellular telephone application that can be used in accordance with embodiments of the present invention; and

0016<figref idref="DRAWINGS">FIG. 7</figref> is a schematic cross-sectional view of a lens mechanism whereby control of lens movement is by magnetic force in accordance with embodiments of the present invention.

DETAILED DESCRIPTION

0017In the drawings, like numbers designate like or substantially similar drawing elements. Well-known elements (e.g., power supplies, electrically conductive lines, etc.) are omitted so as to more clearly show the invention.

0018Referring now to <figref idref="DRAWINGS">FIG. 1</figref>, a schematic cross-sectional view illustrating a lens mechanism in accordance with an embodiment of the present invention is indicated by the general reference character <b>100</b>. Lens <b>2</b> is positioned on lens support post <b>4</b> that rests on flexible support <b>6</b>. As shown in <figref idref="DRAWINGS">FIG. 2</figref>, lens <b>2</b> is a convex lens having a curved top surface farthest from the underlying sensor and a flat bottom surface nearest the underlying sensor. The shape of lens <b>2</b> is illustrative of various single and compound lens shapes and/or combinations of lenses. Electrostatic actuator <b>8</b> is positioned near the edge of lens <b>2</b>. In one embodiment, actuator <b>8</b> is a stacked metal oxide semiconductor (MOS) device that can hold an electrostatic charge (illustrated by several “+” symbols; either positive or negative charge may be used) at various positions relative to the edge of lens <b>2</b>. In an alternate embodiment, actuator <b>8</b> may include one or more magnets or magnetic material for magnetic-based control of lens movement. A base <b>10</b> supports both flexible support <b>6</b> and electrostatic actuator <b>8</b>. Lens <b>2</b> has an optical axis <b>12</b>, on which exists a focus of lens <b>2</b>. Sensor <b>14</b> (e.g., an array of charge-coupled devices (CCDs), or complementary metal oxide semiconductors (CMOS), or both together) is positioned such that sensor <b>14</b> senses electromagnetic (photon) energy (e.g., visible light, infrared, ultraviolet, etc.) passing through lens <b>2</b>. Sensor <b>14</b> is positioned in or on substrate <b>16</b> (e.g., silicon semiconductor wafer). As shown in <figref idref="DRAWINGS">FIG. 1</figref>, lens <b>2</b> is in a first position <b>18</b> and is aligned with geometric plane <b>20</b>. Optical axis <b>12</b> is therefore substantially perpendicular to geometric plane <b>20</b>.

0019In accordance with embodiments of the present invention, if the amount and/or polarity of electrostatic charge on actuator <b>8</b> changes, lens <b>2</b> moves as a result. As shown in <figref idref="DRAWINGS">FIG. 1</figref>, in one embodiment lens <b>2</b> moves upward, away from sensor <b>14</b>, from position <b>18</b> to position <b>22</b> if the electrostatic charge changes on actuator <b>8</b>. In this illustrative embodiment, several additional actuators <b>8</b> (not shown) are positioned around the edge of lens <b>2</b> such that a substantially equal change in charge on each unique actuator <b>8</b> causes lens <b>2</b> to remain substantially parallel to geometric plane <b>20</b>. Therefore, in this illustrative embodiment, in position <b>22</b>, lens <b>2</b> is aligned with another geometric plane <b>24</b>. Optical axis <b>12</b> is substantially perpendicular to geometric plane <b>24</b>, and therefore geometric plane <b>24</b> is substantially parallel to geometric plane <b>20</b>. For clarity in the drawing, flexible support <b>6</b> is not shown in a new position, but it is understood that flexible support <b>6</b> moves to allow lens <b>2</b> to move. In some embodiments, charge on actuator <b>8</b> is changed to cause lens <b>2</b> to move downward, closer to sensor <b>14</b>, from position <b>18</b>. Flexible support <b>6</b> is described in greater detail below with reference to <figref idref="DRAWINGS">FIG. 5</figref>.

0020As shown in <figref idref="DRAWINGS">FIG. 1</figref>, lens <b>2</b> moves so that, for example, an image focus or magnification changes with respect to sensor <b>14</b>. The focus and/or magnification changes as the charge on actuator <b>8</b> changes. Such focus and/or magnification change is a useful feature in, for instance, a camera such as those incorporated into cellular telephone handsets.

0021Referring now to <figref idref="DRAWINGS">FIG. 2</figref>, a schematic cross-sectional view illustrating a lens mechanism in accordance with another embodiment of the present invention is indicated by the general reference character <b>200</b>. The structural elements shown in <figref idref="DRAWINGS">FIG. 2</figref> are substantially the same as in <figref idref="DRAWINGS">FIG. 1</figref>. <figref idref="DRAWINGS">FIG. 2</figref> illustrates that lens <b>2</b> can be moved such that optical axis <b>12</b> tips from its original orientation to new orientation <b>12</b><i>a</i>. As shown in <figref idref="DRAWINGS">FIG. 2</figref>, a change in the electrostatic charge on actuator <b>8</b> causes lens <b>2</b> to move from position <b>18</b> to position <b>26</b>. In one embodiment, moving lens <b>2</b> from position <b>18</b> to position <b>26</b> is done by changing the electrostatic charge on a single actuator <b>8</b>. In accordance with other embodiments, moving lens <b>2</b> from position <b>18</b> to position <b>26</b> is done by changing the electrostatic charge on two or more unique actuators <b>8</b> (not shown) by different amounts. In position <b>26</b>, lens <b>2</b> is aligned with geometric plane <b>28</b>, and the new optical axis is shown as <b>12</b><i>a</i>. Optical axis <b>12</b><i>a </i>for position <b>26</b> is not substantially perpendicular to geometric plane <b>20</b>, as optical axis <b>12</b> is for position <b>18</b>. Therefore, geometric plane <b>28</b> intersects geometric plane <b>20</b>. It can be seen that lens <b>2</b> may be tipped in various directions, depending on the positions and/or changes in charge on two or more actuators <b>8</b> positioned around lens <b>2</b>.

0022As illustrated in <figref idref="DRAWINGS">FIGS. 1 and 2</figref>, lens <b>2</b> moves so that, for example, the position of an image is moved with respect to the sensing surface of sensor <b>14</b>. In this fashion, the position of an image with reference to sensor <b>14</b> is controlled by changes in actuator <b>8</b> charge. Such position variations include movement through substantially parallel planes as well as tipping in various directions.

0023Referring now to <figref idref="DRAWINGS">FIG. 3</figref>, a schematic top plan view of a lens mechanism in accordance with embodiments of the present invention is shown and indicated by the general reference character <b>300</b>. The view in <figref idref="DRAWINGS">FIG. 3</figref> is downwards through lens <b>2</b> along a path that light travels to be incident on sensor <b>14</b>, for example. As shown in <figref idref="DRAWINGS">FIG. 3</figref>, flexible support <b>6</b> is made of several (four are shown) serpentine-shaped elements extending from base <b>10</b> inwards to a center support portion <b>30</b>. The substantially serpentine-shaped elements are illustrative of various flexible support shapes that may be used that allow lens <b>2</b> to move along its optical axis, as shown in <figref idref="DRAWINGS">FIG. 1</figref>, to tip its optical axis, as illustrated in <figref idref="DRAWINGS">FIG. 2</figref>, or both move and tip together. In the embodiments shown, flexible support <b>6</b> is resilient such that lens <b>2</b> returns to the same position when substantially no charge is on the one or more actuators <b>8</b>. Other less resilient materials may be used in other embodiments, in which case lens <b>2</b> is kept in position at all times by charge on the one or more actuators <b>8</b>. In some embodiments, flexible support <b>6</b> is made to be transparent (either due to material properties or thickness, or both). In other embodiments, the image area blocked by flexible support <b>6</b> is small enough so as to not be a concern relative to the overall image falling on underlying sensor <b>14</b>. Lens support post <b>4</b> is likewise made transparent enough or small enough to not materially affect the desired sensing. Lens support post <b>4</b> is positioned on center support portion <b>30</b>, and lens <b>2</b> is positioned over lens support post <b>4</b>. A transparent electrostatic layer, discussed in detail below, is positioned under lens <b>2</b> and over support post <b>4</b>. As shown in <figref idref="DRAWINGS">FIG. 3</figref>, four actuators <b>8</b> are positioned on base <b>10</b> to be equally spaced around lens <b>2</b> and the underlying electrostatic layer.

0024Referring now to <figref idref="DRAWINGS">FIG. 4</figref>, a schematic perspective cutaway view of a lens mechanism in accordance with embodiments of the present invention is shown and indicated by the general reference character <b>400</b>. The view of <figref idref="DRAWINGS">FIG. 4</figref> is taken generally along cut line A-A of <figref idref="DRAWINGS">FIG. 3</figref>. Actuators <b>8</b> are omitted from <figref idref="DRAWINGS">FIG. 4</figref> for clarity. In some embodiments, flexible support <b>6</b> is fabricated from the same one or more layers that make base <b>10</b>. In other embodiments, flexible support <b>6</b> is fabricated from material different from base <b>10</b>. In one embodiment, flexible support <b>6</b> is made of optically transparent glass, such as nitride glass (SiN).

0025<figref idref="DRAWINGS">FIG. 4</figref> shows substantially transparent electrostatic layer <b>32</b> positioned under lens <b>2</b>. In other embodiments, electrostatic layer <b>32</b> may be positioned over, or between portions of, lens <b>2</b>. Electrostatic layer <b>32</b> receives (electrically conductive traces are not shown) and holds an electrostatic charge. Electrostatic layer <b>32</b> may be constructed of niobium oxide (Nb_xO_y), for example. Lens <b>2</b> is made to move by changing the amount or polarity of charge on either or both electrostatic layer <b>32</b> and one or more actuators <b>8</b>. The charge differential between the charges on electrostatic layer <b>32</b> and on the one or more actuators <b>8</b> determines the movement amount and direction of lens <b>2</b>. Of course, electrostatic layer <b>32</b> may be another shape, such as a square or other shape as suitable for a particular implementation. Further, opposite charge polarities may be stored on opposing sides. For example, if support post <b>4</b> is made of Nb_xO_yinstead of SiN (which is a dielectric), both “+” and “−” polarities can be used. One or more transistors can be used to provide the positive and negative biases. Charge may, for example, flow through electrostatic layer <b>32</b> to support post <b>4</b> to flexible support <b>6</b> to a ground line.

0026Referring now to <figref idref="DRAWINGS">FIG. 5</figref>, a schematic cross-sectional view illustrating lens movement on a flexible support according to embodiments of the present invention is indicated by the general reference character <b>500</b>. <figref idref="DRAWINGS">FIG. 5</figref> shows an embodiment of lens <b>2</b> as it moves on flexible support <b>6</b>. <figref idref="DRAWINGS">FIG. 5</figref> illustrates the relation between electrostatic layer <b>32</b> and the one or more actuators <b>8</b>. As discussed above, a change in charge position and/or amount in an actuator <b>8</b> causes lens <b>2</b> to move upwards as flexible support <b>6</b> flexes and adapts. In the example shown, MOS transistors may be used to implement actuator <b>8</b> by allowing different levels of charge to be applied, such as one, two, or three times a baseline amount of charge. The total charge may be in linearly distributed increments. Accordingly, actuator charge may be varied in discrete increments. Alternatively, a continuous charge control on the actuator may be employed. Thus, analog or digital charge control means can be used.

0027As shown in <figref idref="DRAWINGS">FIG. 5</figref>, the distance between electrostatic layer <b>32</b> and the actuator <b>8</b> charge points (e.g., charged regions of MOS transistors) is relatively small. In another embodiment, the electrostatic repulsive force between electrostatic layer <b>32</b> and the actuator <b>8</b> charge points is large enough to cause the edge of lens <b>2</b> to move above the top of one or more actuators <b>8</b>. In some embodiments an attractive electrostatic force exists between actuators <b>8</b> and electrostatic layer <b>32</b>, in others a repulsive force exists, and in still others a combination of attractive and repulsive forces exists. In some embodiments one charge polarity is placed at one end of a single actuator <b>8</b>, and the opposite charge polarity is placed at the opposite end of the single actuator <b>8</b>. In other embodiments, one or more actuators <b>8</b> have one charge polarity and another one or more of actuators <b>8</b> have the opposite charge polarity.

0028In one embodiment, lens <b>2</b> is made of optically transparent glass, such as silicon oxide (SiO₂). Also, support post <b>4</b> and flexible support <b>6</b> are in one embodiment made of optically transparent glass, such as nitride glass (SiN). Electrostatic layer <b>32</b> may be constructed of niobium oxide (Nb_xO_y). Other materials used to fabricate semiconductor and/or microelectromechanical (MEM) machines may be used for these and the other structures shown and described, and fabrication may be done using known semiconductor and MEM machine fabrication procedures.

0029The space surrounding lens <b>2</b> may be filled with air, other gas, or may be a substantial vacuum. In some embodiments the lens apparatus is sealed from the ambient environment, and in other embodiments the lens apparatus is open to the ambient environment. The charges on actuators <b>8</b> may be variable by discrete or continuous amounts, controlled by either digital or analog control signals. In some embodiments, the charge position is moved on the one or more actuators <b>8</b>, such as by charging two or more address electrodes in an addressable circuit (not shown). Control circuitry (not shown) for the actuators <b>8</b> may be formed in or on a portion of base <b>10</b>, or may be separate from base <b>10</b>.

0030Referring now to <figref idref="DRAWINGS">FIG. 6</figref>, a diagram of a cellular telephone application that can be used in accordance with embodiments of the present invention is shown and indicated by the general reference character <b>600</b>. The exemplary cellular telephone shown can include standard features, such as keypad <b>602</b> and display screen <b>604</b>, and is generally capable of capturing still images or moving images, or both. In addition, camera lens <b>606</b> can be included for digital pictures. Camera lens <b>606</b> may be, for example, lens <b>2</b> as described herein. Further, zoom control <b>608</b> can be included to control the position of camera lens <b>606</b> in accordance with embodiments of the present invention. Zoom control may also be implemented via keypad <b>602</b> or other control, such as touch screen, or automatic camera focusing. If a zoom control <b>608</b> button is employed, the button can activate a zooming via a movement of camera lens <b>606</b>. For example, zoom control may activate one or more actuators <b>8</b> so as to effect movement of camera lens <b>606</b> for zooming, as discussed above. While an exemplary stand-alone camera has been shown, camera lens <b>606</b> and zoom control <b>608</b> may be incorporated into various other electronic devices in accordance with embodiments. Further, zoom control <b>608</b> may also be used to control image focus in either a manual or an automatic fashion.

0031<figref idref="DRAWINGS">FIG. 7</figref> is a schematic cross-sectional view of an embodiment in which lens movement is controlled by magnetic force, shown and generally indicated by reference character <b>700</b> for a magnetically actuated lens movement mechanism formed, e.g., on a semiconductor substrate in accordance with MEMS fabrication methods. As shown in <figref idref="DRAWINGS">FIG. 7</figref>, electrically conductive coil <b>702</b> (one or more loops) is formed in layer <b>704</b> underlying lens <b>706</b>. Coil <b>702</b> acts as a magnet if electrical current flows in coil <b>702</b>. Coil <b>702</b> is, e.g., aluminum or titanium, and is positioned such that the coil is around the perimeter of lens <b>706</b> so that coil <b>702</b> does not block light passing through the center of lens <b>706</b>. Electrically conductive traces between coil <b>702</b> and a current source (either on the semiconductor substrate or on, e.g., a separate integrated circuit chip) are not shown. In another embodiment, coil <b>702</b> is formed integral with lens <b>706</b> or in a layer overlying lens <b>706</b>. In yet another embodiment, two or more coils <b>702</b> are used. One or more actuators <b>708</b> (only one is shown) contain magnets (e.g., electrically conductive loops <b>709</b> in which electrical current flows). As shown in <figref idref="DRAWINGS">FIG. 7</figref>, actuators <b>708</b> are positioned near the perimeter of lens <b>706</b>. In other embodiments, actuators <b>708</b> are positioned over or under lens <b>706</b>. The attractive or opposing magnetic force(s) between actuator(s) <b>708</b> and the force generated by coil <b>702</b> causes lens <b>706</b> to move, as described above. Various magnetic configurations are possible, including varying (discrete steps or analog) current in loop <b>702</b>, varying (discrete steps or analog) current in one or more actuators <b>708</b>, or replacing the electromagnets with fixed magnets (e.g., Nickel Iron compounds).

0032Although the invention has been described with respect to specific embodiments thereof, these embodiments are merely illustrative, and not restrictive, of the invention. For example, various other configurations are possible, such as the lens being positioned between the flexible support and the sensor, or the electrostatic layer being positioned over the lens, or the electrostatic layer being various shapes dissimilar to that of the lens's outline. The actuators <b>8</b> may be placed at various positions to the side, above, or below lens <b>2</b>. Also, the invention is described in terms of MEMS technology, which although small is generally considered larger than molecular nanotechnology (structures less than approximately 100 nm). Embodiments include molecular nanotechnology structures.

0033In the description herein, numerous specific details are provided, such as examples of components and/or methods, to provide a thorough understanding of embodiments of the present invention. One skilled in the relevant art will recognize, however, that an embodiment of the invention can be practiced without one or more of the specific details, or with other apparatus, systems, assemblies, methods, components, materials, parts, and/or the like. In other instances, well-known structures, materials, or operations are not specifically shown or described in detail to avoid obscuring aspects of embodiments of the present invention.

0034Reference throughout this specification to “one embodiment”, “an embodiment”, or “a specific embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention and not necessarily in all embodiments. Thus, respective appearances of the phrases “in one embodiment”, “in an embodiment”, or “in a specific embodiment” in various places throughout this specification are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics of any specific embodiment of the present invention may be combined in any suitable manner with one or more other embodiments. It is to be understood that other variations and modifications of the embodiments of the present invention described and illustrated herein are possible in light of the teachings herein and are to be considered as part of the spirit and scope of the present invention.

0035Embodiments of the invention may be implemented by using a programmed general purpose digital computer, by using application specific integrated circuits (ASICs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), optical, chemical, biological, quantum or nanoengineered systems, components and mechanisms may be used. In general, the functions of the present invention can be achieved by any means as is known in the art. Distributed, networked systems, and/or components and circuits can be used. Communication, or transfer, of data may be wired, wireless, or by any other means.

0036It will also be appreciated that one or more of the elements depicted in the drawings/figures can also be implemented in a more separated or integrated manner, or even removed or rendered as inoperable in certain cases, as is useful in accordance with a particular application. It is also within the spirit and scope of the present invention to implement a program or code that can be stored in a machine-readable medium to permit a computer to perform any of the methods described above.

0037Additionally, any signal arrows in the drawings/FIGS. should be considered only as exemplary, and not limiting, unless otherwise specifically noted. Furthermore, the term “or” as used herein is generally intended to mean “and/or” unless otherwise indicated. Combinations of components or steps will also be considered as being noted, where terminology is foreseen as rendering the ability to separate or combine is unclear.

0038As used in the description herein and throughout the claims that follow, “a”, “an”, and “the” includes plural references unless the context clearly dictates otherwise. Also, as used in the description herein and throughout the claims that follow, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.

0039The foregoing description of illustrated embodiments of the present invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed herein. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes only, various equivalent modifications are possible within the spirit and scope of the present invention, as those skilled in the relevant art will recognize and appreciate. As indicated, these modifications may be made to the present invention in light of the foregoing description of illustrated embodiments of the present invention and are to be included within the spirit and scope of the present invention.

0040Thus, while the present invention has been described herein with reference to particular embodiments thereof, a latitude of modification, various changes and substitutions are intended in the foregoing disclosures, and it will be appreciated that in some instances some features of embodiments of the invention will be employed without a corresponding use of other features without departing from the scope and spirit of the invention as set forth. Therefore, many modifications may be made to adapt a particular situation or material to the essential scope and spirit of the present invention. It is intended that the invention not be limited to the particular terms used in following claims and/or to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include any and all embodiments and equivalents falling within the scope of the appended claims.